The proposed study falls into three related sections: 1) Investigation of the binocular aspects of amblyopia and microtropia pathogenesis includes study of hereditary patterns of stereopsis ability in families of amblyopes and heterotropes, determination of incidence of stereoblindness syndrome in test population and its correlation with microtropia incidence, using precise computer-based cover and n-diopter prism tester to determine if there is a population of sub-clinically-detectable population of truly "micro" microtropes. 2) Continuation of present study of screening of young children and infants for amblyopia and strabismus, using already proven stereotest and new automated tester for ascertaining phoria or tropia status as second-level test mode following failure on stereo screening but prior to referral. 3) Investigation of a new optical treatment for amblyopia and suppression involving "occlusion" with neutral density filters bilaterally to maintain patient's visual system at mesopic adaptation levels.